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Chapter 12: Suboccipital Craniectomy/Foramen Magnum Decompression 119

on occasion completely excised; however, exposure is generally tate adequate decompression. Copious amounts of CSF will flood
limited and may require combination with a rostrotentorial the surgical site and require suctioning. Next, a duroplasty is
craniectomy and occlusion of the transverse sinus [4]. The use performed using sheet of a commercially available porcine submu-
of an ultrasonic surgical aspirator improves the opportunity for cosal product or a synthetic dural replacement to serve as scaffold-
tumor removal and biopsy. ing for regrowth of the dura.
The most frequently encountered indication for a suboccipital The material is cut to the desired size and sutured in a tent‐like
craniectomy is surgical treatment of Chiari‐like malformation. In fashion using simple interrupted sutures of a 5‐0 or 6‐0 absorbable
this procedure, the meninges are incised in the manner described synthetic monofilament suture (Figure 12.13) [9]. In most patients,
earlier and are then marsupialized by suturing laterally to the adja- four simple interrupted sutures are placed on each side to connect
cent muscle fascia using 5‐0 or 6‐0 absorbable synthetic monofila- the duroplasty material to the marsupialized dura, and then one
ment suture. Usually two simple interrupted sutures on each side suture rostrally and caudally if necessary. A watertight seal does not
are sufficient. Frequently in this condition, the cerebellum is found appear necessary as is often stated in the human neurosurgical
extending under the dorsal arch of C1. Approximately one‐third to literature.
half of the dorsal arch is removed with Kerrison rongeurs to facili- After achieving complete hemostasis, a previously obtained fat
graft from the gluteal region is rinsed with saline and placed over
the duroplasty (Figure 12.14), followed by a sheet of absorbable
gelatin foam. The fat graft is usually 5–7 mm thick and of sufficient
size for an anticipated 30% reduction in size during the revasculari-
zation phase [10].
The incision is closed beginning with apposing the dorsal cervi-
cal musculature on the midline in a simple continuous pattern with
monofilament absorbable suture. If necessary, muscle attachments
can be sutured rostrally to remaining muscle attachments to the
occipital bone or to the temporalis fascia. The subcutaneous tissues

Figure 12.12 6‐0 stay sutures placed through the lateral aspect of the incised
meninges to maintain traction and improve exposure.

Figure 12.13 Intraoperative photograph showing nearly completed duro-
plasty using a sheet of commercially available porcine submucosal product
(arrow). This product is placed over the exposed cerebellum and cervical
spinal cord in surgery for Chiari‐like malformation. This material is cut to
the desired size and sutured to the edges of the cut meninges in a tent‐like
fashion using simple interrupted sutures of 5‐0 or 6‐0 absorbable synthetic Figure 12.14 A fat graft is positioned over the craniectomy site. This is often
monofilament suture. The duroplasty is intended to serve as scaffolding for covered with an absorbable gelatin sponge and the musculature is sutured
regrowth of the dura and also serves to protect the underlying neural tissue over the graft. (Inset) Sagittal T2‐weighted MRI shows the fat graft in place
from adhesions. 2 years after surgery (arrow).